This invention relates gerenally to gas-tight closure and more particularly it relates to a closure for sealingly closing an outlet opening of a feeding duct communicating with a loading space. The closure is provided with a control member which is arranged outside the feeding duct.
Closures of this kind are employed for shutting off feeding streams of different loose materials such as, for example, of preheated coal. The loose material in process is discharged through a feeding duct provided with the open closure into a feeding space which is to be subsequently closed. As soon as the feeding space is charged with the required amount of the material, the flow of the latter is shut off and the inlet opening is hermetically sealed by the closure. Any escape of gases during the closing period both from the charge space and generally from the range above the closing device in the duct should be avoided. Furthermore, it is important that the charge space in the vicinity of the closure should be free of deposited particles so as to insure a flawless feeding operation into the space and a clean seal of the closure.
Closures are known in which the sealing device has approximately a conical configuration having its conical surface (conical jacket) inclined about 45.degree. relative to the axis of the cone which is compressed against the rim of the inlet opening of the space to be charged. This inlet opening usually has a stable knife-edge like rim on its ends to be sealed. A feeding duct through which the loose material flows is fixedly connected to the opposite rim of the inlet opening. The sealing device is axially displaced by means of a spindle or the like, located outside the filling space and operated so as to firmly abut against this inlet opening.
One of the disadvantages of such prior art closures is the fact that particles of the loose material or other foreign bodies which accidentally adhere to the sealing surfaces or the deformations caused by heating effects prevent frequently the closure from establishing a gas-tight seal. Moreover, the force with which the sealing device is compressed on the rim of the inlet opening depends individually on persons operating the closure; it is true, that such known closure might be equipped with a hydraulic or pneumatic control device which exerts a precisely definable force but such control devices require continuous maintenance and attention and under certain circumstances introduce additional disturbing factors.